Therapeutic electrical stimulation (TES) is a modified form of traditional electrical stimulation which involves the use of low-intensity, sub- threshold electrical stimulation applied during sleep. TES is well tolerated and has been used since 1988 in Canada for children with a variety of neuromuscular conditions. The efficacy of TES has not yet been examined in the child with juvenile rheumatoid arthritis (JRA). The purpose of this R29 proposal is to develop and test this innovative use of low-level muscle electrical stimulation as an adjunctive therapy to minimize or prevent movement limitations in the child with juvenile rheumatoid arthritis. Twenty JRA children with bilateral knee joint involvement will be studied during six months while using nocturnal TES as an adjunct to a physical therapy home program. This low-level subthreshold stimulation is done while the child is sleeping six nights a week. This study is very realistic for the child with juvenile rheumatoid arthritis as it done during sleep, the technology is noninvasive, easy to learn and does not add to "the burden of care." The electrical stimulation will be done unilaterally to allow the other leg to serve as a control. The child will be monitored in three major ways: clinical exam, quantitative muscle strength and muscle bulk, and functional assessments. The monthly clinical exam will document bilateral lower extremity A/PROM, MMT of key functional lower extremity muscle groups, leg length, thigh circumference and the Kraus-Weber flexibility test score. The quantitative muscle strength will be assessed by monthly isometric knee extensor torque measurements. The functional assessment will include monthly Childhood Health Assessment Questionnaire (CHAQ), and a modified Pediatric Evaluation of Disability Inventory (PEDI). At the beginning and end of the 6 month period, a gait analysis study including physiologic cost index as well as ultrasound measurement of quadriceps muscle thickness will be done. Our hypothesis is that nocturnal therapeutic electrical stimulation will minimize quadriceps weakness and/or atrophy thereby reducing the potential impairments of muscle weakness, knee flexion contracture and gait deviations which may contribute to long-term disability in the JRA population. If the efficacy of this intervention in preserving mobility is demonstrated, future research would explore the underlying neuromuscular and neuroendocrine mechanisms responsible for the clinical effect.